Cobra 19 DX IV mods???

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Cobra 19 DX IV mods???

Postby Boss Hogg » Monday 4th Sep 2006, 3:57

Ok I'm new to this CB thing and I was wandering if there are any mods I can do to this CB? Any help will be appreciated.
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Postby Turkish » Friday 20th Apr 2007, 4:50

I also have one of these cheep-o starter radios that I would like to play with just to see how much wattage I can push out of it. Anyone have info on it?
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Postby kc8mob » Friday 20th Apr 2007, 5:40

Well of course I do! :D

Now let me dig it up.

First off, though. If you can post some pics of the inside of the rig (Parts side) it would help allot.
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Postby kc8mob » Friday 20th Apr 2007, 5:46

Ok for starters, Cobra 19 DX {L5, L6, L801, RV2}

The Ls are inductors. Maybe open coils or coils with slugs that can be tuned with a screw driver. RV2 is going to be your modulation adjustment.

You can add a super swing kit to just about any radio, I just have to find out where to put it in in this radio.
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Postby Turkish » Friday 20th Apr 2007, 6:10

I sure will let me take a few pics of the inside... ok here is one the rest are on photo bucket
Image
there is one pic to get you started if you need more or of a certain area just let me know
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Postby Turkish » Friday 20th Apr 2007, 6:45

oh and this is a DX 4 so the parts you posted earlier are not correct my cans are named LR1 LR2LT1 LR4 LR5 then i have RVM1 RVQ1 RVQ3 lol yeah i think that is it
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Postby kc8mob » Friday 20th Apr 2007, 12:30

Ok well the little white and blue pot by the transformer is your modulations. And to super swing that radio, you'll have to pull the inductor that feeds the RF driver. The inductor there looks like a resistor and is green. On top of that you have to leave the inductor in and just pull the voltage side. Install a cap and you have to play with the resistor value.

This is just like a Maxon radio you can buy at walmart. It'll actually get loud as hell. You'll only get about 15 watts pep out of them though.
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Postby 11mfrftr » Tuesday 10th Jul 2007, 15:08

can someone show me or give a number of the inductor to super swing the radio...and what kind of cap.? Also what part is the transformer so i can adjust that pot.?
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Postby ramblingman » Wednesday 11th Jul 2007, 10:50

hi there,youll probally need about a 220 uf capacitor,and somewhere between a 50-100 ohm resistor.the idea is to locate the 13.8 volt dc feed,to the driver section,disconnect it by either cutting the land pattern on the solder side of the pcb.or either disconnecting the proper resistor,choke,or capacitor,whatever the case maybe.what i gently do is locate the pcb land pattern feeding the driver stage,using a exacto knife,gently cut the land pattern,completely isolating it.then install my 220 uf capacitor,on the componet side of the board,then install my 50-100 ohm resistor across the capacitor,on the solder side of the board.remember the negative side of the capacitor,needs to be towards,the driver....usually a 50 ohm resistor,gives you about 2 watt dead key,thats gently about right.
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COBRA DX IV

Postby doctor » Thursday 21st Aug 2008, 15:09

Just change mics, put an amplified mic on it, and it really goes to town.....

POWER 18-20 watts....

I wonder if one can add a lower chnls to it


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cobra 19 dx iv

Postby doctor » Thursday 21st Aug 2008, 15:18

I wonder if it is easy to put the lower channels in this radio...

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cobra 19 dx iv

Postby WARLORD136 » Tuesday 26th Aug 2008, 12:04

why fool with a swing kit, lower chls and all that when you could get a radio with all that in it for about $150.00, echo included?
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Cobra 19 DX IV mods???

Postby CHOAB » Thursday 27th Nov 2008, 13:18

When I modded the 19 Ultra III (19 DX IV without RF gain), I cut the mod limiter, tuned the output coils, and with a 13.8v supply i was able to do 7 watts swinging almost 9 watts into the dummyload.

I would much rather the radio have a low dead key, I read the post above that suggested putting a 220uf cap and a resistor before the voltage leg of the final... but its alot easier said than done on this board....
has anyone done this yet?
Last edited by CHOAB on Monday 23rd Feb 2009, 18:16, edited 1 time in total.
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Re: Cobra 19 DX IV mods???

Postby fsjonsey » Saturday 21st Feb 2009, 16:10

I've been messing around with a 19 Ultra III lately for the hell of it. I replaced the stock final with a IRF520 MosFET, just to see if I could, using a homebuilt equivalent of an ERF en-1230 companion part. With a little tweaking, the radio now dead keys at 2 watts, swinging to 10+. I'm wondering what else I could to to get a little more power out of it? These little radios are great for mounting in newer cars where space is hard to come by.
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Re: Cobra 19 DX IV mods???

Postby troyboy162 » Sunday 22nd Feb 2009, 18:59

very interested in anyones findings on this radio. in perticular will increases in the radios power be seen in the output to the PA as well?

i found this post but the all imported picture does not show
http://www.cbradiotalk.com/viewtopic.ph ... highlight=
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Re: Cobra 19 DX IV mods???

Postby 631up » Monday 23rd Feb 2009, 17:25

ok heres my NEW cobra 19 mod,

add 1 cup sugar
2 cups spice
and 1 tablespoon of everything nice
Last edited by 631up on Tuesday 24th Feb 2009, 7:23, edited 1 time in total.
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Re: Cobra 19 DX IV mods???

Postby The Defpom » Monday 23rd Feb 2009, 22:30

Thanks for posting the info, however, your post is on the verge of being a bit too abusive... be careful, abusive comments are not tolerated.
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Re: Cobra 19 DX IV mods???

Postby 631up » Tuesday 24th Feb 2009, 7:27

ok there i fixed it.

I just figured since everyones trying to abuse this radio, i'd share my mod in an abusive fashion.
but it's fixed now
:D :D :D :D :D :D :D :D

-631
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Re: Cobra 19 DX IV mods???

Postby The Defpom » Tuesday 24th Feb 2009, 7:39

OK, but why did you remove the mod info you posted ?
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Re: Cobra 19 DX IV mods???

Postby 631up » Tuesday 24th Feb 2009, 8:30

i didn't!!! it's the sugar and spice mod :P :dance:
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Re: Cobra 19 DX IV mods???

Postby 631up » Tuesday 24th Feb 2009, 8:35

ok sorry im being a jerk....

heres the mod in condensed form... 3 steps
remove limiter.
remove dm2 and replace with a jumper
spread LT5 (not too much... don't be gay!)
Last edited by 631up on Monday 21st Dec 2009, 6:30, edited 3 times in total.
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Re: Cobra 19 DX IV mods???

Postby CHOAB » Tuesday 24th Feb 2009, 8:50

Here is a picture of the Cobra 19 DX IV / ULTRA audio limiter diode that the famous 631 mentioned, as you can see I desoldered one leg incase I decided to put it back (good enough). I did not add a capacitor and resis on DM2 to lower deadkey though I would reccomend that for driving a linear amplifier.

Image



I DO NOT RECCOMEND this next mod because you can damage your radio, and/or add distortion to your audio. This radio is a Cobra 19 ULTRA (cobra19 DX IV without RF gain) which sells at walmart for $35 US dollars. After desoldering the Audio limiter, I neatly spread these 4 inductor coils pictured below which brought my radio from the factory 2.5 watts RMS @13.8 volts, to 7.5 WattsRMS deadkey and swinging 9 wattsRMS. The microphone is an Astatic D104 power mic.


Image




This is not a mod you want to do if your going to drive an amplifier, I did it because its being used "barefoot" and now it has almost 4x the power.

This radio is installed in my brothers car that is used regularly with no problems. The radio has LOUD clear audio, looks and fits great in compact spaces. Unfortunately its a cheap radio so the recieve is garbage (no filtering/noise blank) so you may pickup ignition noise. Still not bad for 35 DOLLARS at walmart!

I can post more info/pics if anyone wants. Good Luck!
- STUNTMAN 311
Last edited by CHOAB on Thursday 26th Feb 2009, 2:42, edited 1 time in total.
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Re: Cobra 19 DX IV mods???

Postby 631up » Saturday 14th Mar 2009, 9:25

Hmm...
I found out those chokes are there to filter harmonics.....

You will gain watts on the meter by doing this... but...

How many of those watts are on 27mhz?
good question???...
anyone have a spectrum analyzer??
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Re: Cobra 19 DX IV mods???

Postby hyper7driver » Sunday 23rd Aug 2009, 11:13

I tried those mods today in the pictures. I un-soldered the DM-1 diode on one end as shone and gained a little dead key, about 2 watts, and it would swing a bit above five, about eight or so with stronger vocals. I messed with the blue/white knobs inside. The one under the clump of wires, RVQ1 if I remember right simply adjusted the squelch knob, the one off to the side seemed to affect power but only slightly, (seemed the best set in the middle,) and the one closest to the back, RM?? it was labeled gave some more power when I turned completely counterclockwise. Then I started messing with the coils, a little at a time, and the only one that gave me any improvement was messing with the LT7. And over doing it is easy, so I guess you could be gay if you're not careful? But after tweaking the LT7 coil, adjusting the knobs, pinching all the other coils back together, and un-hooking the DM1 diode, my little 19 Ultra-3 now proudly dead keys in the 5-6 watt range, and will swing over ten watts with no problem, and even a little above 15 watts with strong, but no where near yelling vocals, all with a stock mike and no distortion according to a few radio checks. I'm actually proud of my little 19.

Thanks for all the help guys. The advice gave me the confidence to do this, and I actually enjoyed playing with my radio This is my first mod by the way.
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Re: Cobra 19 DX IV mods???

Postby titofish » Friday 7th Sep 2012, 1:53

Hi all. I did remove de diode limiter and spread the coils. It work, but then a distorted audio was the report other cb'rs gave. I want to fix it but dont know how. Any help will be appreciated. Thanks
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